PGPLOT Module: PGENV -- set window and viewport and draw labeled frame


SUBROUTINE PGENV (XMIN, XMAX, YMIN, YMAX, JUST, AXIS)
REAL XMIN, XMAX, YMIN, YMAX
INTEGER JUST, AXIS

Set PGPLOT "Plotter Environment". PGENV establishes the scaling
for subsequent calls to PGPT, PGLINE, etc. The plotter is
advanced to a new page or panel, clearing the screen if necessary.
If the "prompt state" is ON (see PGASK), confirmation
is requested from the user before clearing the screen.
If requested, a box, axes, labels, etc. are drawn according to
the setting of argument AXIS.


Arguments
XMIN (input) : the world x-coordinate at the bottom left corner
of the viewport.
XMAX (input) : the world x-coordinate at the top right corner
of the viewport (note XMAX may be less than XMIN).
YMIN (input) : the world y-coordinate at the bottom left corner
of the viewport.
YMAX (input) : the world y-coordinate at the top right corner
of the viewport (note YMAX may be less than YMIN).
JUST (input) : if JUST=1, the scales of the x and y axes (in
world coordinates per inch) will be equal,
otherwise they will be scaled independently.
AXIS (input) : controls the plotting of axes, tick marks, etc:
AXIS = -2 : draw no box, axes or labels;
AXIS = -1 : draw box only;
AXIS = 0 : draw box and label it with coordinates;
AXIS = 1 : same as AXIS=0, but also draw the
coordinate axes (X=0, Y=0);
AXIS = 2 : same as AXIS=1, but also draw grid lines
at major increments of the coordinates;
AXIS = 10 : draw box and label X-axis logarithmically;
AXIS = 20 : draw box and label Y-axis logarithmically;
AXIS = 30 : draw box and label both axes logarithmically.

For other axis options, use routine PGBOX. PGENV can be persuaded to
call PGBOX with additional axis options by defining an environment
parameter PGPLOT_ENVOPT containing the required option codes.
Examples:
PGPLOT_ENVOPT=P ! draw Projecting tick marks
PGPLOT_ENVOPT=I ! Invert the tick marks
PGPLOT_ENVOPT=IV ! Invert tick marks and label y Vertically